Many implantable medical devices include components that are deployed in particular areas within a human or animal body. In one example, a neurostimulator deployed proximate to targeted tissue includes electrodes that deliver an electrical stimulation therapy to the tissue. In another example, an electrical sensor deployed proximate to a muscle senses activation of the muscle. With these and other implantable devices, it can be desirable that one or more components remain substantially anchored, so that the components will be less likely to migrate from the desired site of sensing or therapy.
Devices that restrict migration of an implanted medical device or a component thereof are called “fixation structures.” Fixation structures can anchor a medical device to an anatomical feature, such as an organ or a bone. Fixation structures do not necessarily restrict all motion of the implanted device or its component, but generally reduce the motion of the device or component so that it remains proximate to a target site.
There have been many approaches that address fixation of medical devices. Some devices, such as a lead described in U.S. Pat. No. 4,269,198 to Stokes, employ fixed protrusions such as tines to engage body tissue. Other devices, such as the electrode assembly disclosed in U.S. Pat. No. 6,704,605 to Soltis et al., use a helical securing structure. U.S. Pat. No. 5,405,367 to Schulman et al. describes the use of barbs to hold a medical device such as a microstimulator in place.
Table 1 below lists documents that disclose some of the many devices and techniques pertaining fixation of medical devices. Some of the devices and techniques employ mechanical fixation structures such as tines or swellable membranes. Others employ adhesive properties to hold devices in place.
TABLE 1PatentNumberInventorsTitle6,714,822King et al.Apparatus and method for expanding astimulation lead body in situ6,704,605Soltis et al.Medical electrode assembly6,697,676Dahl et al.Medical electrical lead having an expandableelectrode assembly6,650,921Spehr et al.Cardiac lead with minimized inside diameterof sleeve6,434,431Camps et al.Intramuscular medical electrical lead withfixation member6,240,322PeterfesoSystem and apparatus having low profileet al.collapsible tines6,181,973Ceron et al.Anchoring structures for implantableelectrodes5,951,597WestlundCoronary sinus lead having expandable matrixet al.anchor5,837,007Altman et al.Intracardiac lead having a compliant fixationdevice5,545,206CarsonLow profile lead with automatic tine activation5,405,367SchulmanStructure and method of manufacture of anet al.implantable microstimulator5,300,107Stokes et al.Universal tined myocardial pacing lead4,658,835PohndorfNeural stimulating lead with fixation canopyformation
All documents listed in Table 1 above are hereby incorporated by reference herein in their respective entireties. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, many of the devices and methods disclosed in the patents of Table 1 may be modified advantageously by using the techniques of the present invention.